The subject of this invention is a needle for perform biopsies, i.e. for removal of pieces of tissue from human or animal bodies. The needle which is the subject of this application is of particular use in performing pleural biopsies.
Needles for performing biopsies are well known and normally comprise a probe which carries near the distal end a scoop projecting from the side of the probe, a biopsy being performed by inserting the probe through an incision made in the skin and pressing the probe into the body far enough for the scoop to reach the position of the body from which a portion is to be removed. The probe is then withdrawn, the scoop entraining a portion of the tissue of the body, and as the probe is removed this portion of tissue held by the scoop is brought back out for medical examination. Such known biopsy needles suffer from the disadvantage that their results are extremely unpredictable and in fact usually a suitable portion of tissue is removed in little more than 70% of such biopsy operations. Even when a satisfactory portion of tissue is removed, this frequently is accompanied by a piece of unwanted tissue Also, the probe may cause more damage than necessary to surrounding tissue and if the tissue sample obtained is unsatisfactory, the needle must be re-inserted into the body and a fresh attempt made to obtain a satisfactory tissue sample.
The International Patent Publication No. WO 89/05608 discloses a biopsy needle which gives a high degree of success in removing satisfactory samples at a first attempt, a success rate normally well above 90%, and which readily removes cleanly a sample of wanted tissue without dragging with it portions of unwanted tissue.
A biopsy needle according to this disclosure incorporates an elongated body pointed at one end having a tissue-removing edge directed backwardly from the pointed end. The tissue-removing edge is formed on a flap supported by the body and is movable between a retracted position, in which the tissue-removing edge lies within the lateral confines of the body, and an extended position in which the tissue-removing edge lies beyond the lateral confines of the body.
The proximal end of the needle, i.e., the end remote from the pointed end, is formed as a handle supporting operating means coupled to the flap and operative to move the flap from the retracted position to the extended position and vice versa.
The operating means includes a means to lock the flap in the chosen position.
The flap may be formed as a flat flap or may be curved in the form of a scoop.
The tissue-removing edge may be formed as a straight edge or may be formed with serrations.
The flap is mounted on a plunger slidable within the tubular body. The wall of the tubular body in this construction is formed with an aperture with which the flap may be brought into register by an appropriate sliding movement of the plunger.
The flap is pivoted at one end to the plunger and is spring-urged to swing outwardly from the plunger, the tissue-removing edge being at the end of the flap remote from the pivot. In an alternative construction the flap may be formed of spring material, is formed at one end with the tissue-removing edge and is attached at the other end to the plunger, the flap being shaped to tend to spring outwardly from the plunger.
The interior of the tubular body preferably has a circular cross section so that the plunger is rotatable as well as slidable in the tubular body.
The handle is tubular and may thereupon be formed with a slot having two axially disposed portions circumferentially spaced and connected at their distal ends by a circumferential portion, one of the axially disposed slot portions being open at its proximal end. The plunger presents a pin engaging the slot, the position of the pin on the plunger and the positions of the various portions of the slot with respect to the tubular body being such that when the pin on the plunger is engaged with the open ended axial portion of the slot the flap is circumferentially displaced from the aperture in the tubular body. The length of this axial portion is such that, when the pin is at the distal end of the slot, the flap is nearer the distal end of the tubular body than the aperture while being still circumferentially displaced from the aperture. Rotating the plunger so that the pin moves along the circumferential portion of the slot to the end where it joins the axial portion of the slot brings the flap into line with the aperture although the flap is still nearer the distal end of the tubular body than the aperture. Then retracting the plunger along this other axial portion of the slot towards the proximal end of the slot brings the flap into register with the aperture in the tubular body and frees the flap to swing out and project through the aperture.
This biopsy needle, while constituting a significant improvement over prior known biopsy needles, has been found to present the drawback that the plunger, which fits loosely within the tubular body, can easily rotate and slidably translate within tube, and can therefore change the relative positions of the flap and aperture or even accidentally become disengaged from the tubular body.